Different types of autoinjectors are frequently used in order to facilitate administration of drugs to patients. When the proximal end of the autoinjector is correctly positioned against the intended area of the skin of the patient, an activation means on the autoinjector is pressed in order to activate the autoinjector. When activated, a needle rapidly punctuates the skin and the drug is delivered via the needle automatically.
There are two different categories of the autoinjectors on the market today. The first one uses custom designed medicament chambers, examples of these are described in WO2003/099358 and WO01/93926, while the second category uses standard pre-filled syringes. There are several advantages directed to the use of standard pre-filled syringes, for example the syringes have already been tested and approved in accordance with present regulations, which saves time and reduces the overall costs for the autoinjector. The present invention is directed to disposable autoinjectors used in combination with standard pre-filled syringes.
Since the autoinjectors are often used for self-administration of a drug to, the punctuation of the patients skin and the delivery of the drug via the needle are preferably performed rapidly which requires that a significant force is applied to the syringe by the drive mechanism. However, syringes are fragile and when the force of the drive mechanism is applied, there is a significant risk that the fragile syringe breaks.